The present invention relates to an improved printed sheet feeding mechanism and method and more particularly to an improved printed sheet feeding mechanism and method for feeding and stacking printed sheets from a continuous web.
As set forth in U.S. Pat. No. 6,234,647 (incorporated herein by reference), single sheets are fed from a printer and accumulated in stacks. Each stack represents a complete project, such as a book or report. The complete stacks are deposited into a cassette in offset relationship to each other so that when the cassette is filled it has a number of offset stacks of printed sheets. The stacks in these cassettes can then be transferred to another machine (such as a finishing machine) in any well known manner, such as that described and shown in U.S. Pat. Nos. 6,192,295 and 6,324,442 (both of which are incorporated herein by reference).
The methods and mechanisms now in use for performing these operations are primarily concerned with feeding and stacking single printed sheets. However, sheets for a project are sometimes printed in side-by-side relationship on a continuous roll with projects of equal number of sheets being printed side-by-side with consecutive sheets on each side and projects of different number of sheets being printed on the continuous roll one project behind the other with consecutive sheets in side-by-side relationship. It may also be desirable to print from webl-to-web and then slit cut and stack the sheets as a separate off-line finishing operation. An example of this would be when a continuous web is fed from a printer with the first printed sheet being the bottom sheet of the web and when unwound would be the last sheet to be processed in any finishing operation. In printing such sheets in side-by-side relationship, if the number of sheets of each project are the same then the two projects can be printed in side-by-side relationship with consecutive sheets on the same side and when the sheets are separated from the web, separate stacks of the same number of sheets can be formed. If the projects are of different lengths requiring stacks of different number of sheets, then the sheets of one project are printed in side-by-side relationship on the web with consecutive sheets in side-by-side relationship and a second project is printed in a side-by-side relationship on the continuous web behind the first project with consecutive sheets in side-by-side relationship. In this instance, the sheets must be separated and merged from a side-by-side relationship to a single file relationship and stacked as separate stacks. Alternately, where the projects are of unequal length, each project can be printed on each side of a web and slit cut and assembled into stacks with blank sheets left over from the side with the shorter project. Existing equipment and methods do not provide for separating the side-by-side sheets from a continuous web, placing the separated sheets into stacks which are offset from each other and placing them into another mechanism such as a cassette.
The present invention provides an improved sheet feeding and stacking mechanism and method for sheets printed on a continuous web in side-by-side relationship.
Another object of the present invention is the provision of an improved sheet feeding and stacking mechanism and method in which the side-by-side printed sheets on a continuous web are separated into separate sheets which are then accumulated in stacks offset from each other and placed into another mechanism, such as a cassette.
Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice